Separation of phenols from hydrocarbon distillates by steam distillation



. w. MILNER 2,437,649

SEPARATION OF PHENOLS FROM HYDROCARBON DISTILLATES BY STEAM DISTILLATIONFiled March 7, 1945 Hydrocarbon Ou/et I I Ana I-yzer" fiandense 9 T l6,9

Sen-Mar Separator l hvfer' & Ii C back /nfermediafe Out/8i- Szeam l2fi-Febof/er j MReboI/er IN V EN TOR.

I avid \Af. Milne? Patented Mar. 9, 1948 SEPARATION OF CARBON 'rmLs'rloDavid William Milner,

to Yorkshire Tar Dis England Application March "1, 1945, Serial no.

In Great Britain November 20,

PHENOLS FROM HYDRO- IIQIISTILLATES BY STEAM DIS- Leeds, England,assignmtillers Limited, Barnsley,

8 Claims. (Cl. 202-42) This invention relates to the separation ofphenols from hydrocarbon distillates.

The usual method-of separating phenols from hydrocarbon distillatesinvolves washing the distillates with a solution of caustic alkali andthen acidifying the aqueous liquor in order to set free the phenolswhich are caused to separate as an oily layer.

The object of the present invention is to provide an improved processfor the separation, without the employment of caustic soda or acids, ofphenols from hydrocarbon distillates which contain hydrocarbon andphenols of closely related boiling points including such distillatesobtained from a continuous tar still or petroleum still.

The invention consists, broadly, in subjecting such hydrocarbondistillates containing phenols which distill along with the hydrocarbonswhen such distillates are vaporized in the absence of steam todistillation in the presence of steam, whereby the major portion of thehydrocarbon components are distilled oif with water in the form of anazeotropic mixture leaving a residue or giving rise in a later stage ofdistillation to a product having a relatively high phenols content.

The invention is particularly applicable to hydrocarbon fractions fromcontinuous stills in which the boiling points of the hydrocarbons andphenols are closely related.

The invention is, however, also applicable to the treatment of mixturesof hydrocarbons and phenols in which there is a substantial differencein boiling points between the constituent hydrocarbons and phenols andis furthermore applicable to mixtures containing in addition tohydrocarbons and phenols other bodies such as tar bases.

Distillation in the presence of steam may be carried out in a continuousmanner by running the mixture of hydrocarbons and phenols down a columnup which steam is blown, the hydrocarbons being taken off at the top andthe phenols at the bottom.

Alternatively, the process may be carried out by blowing steam into abody of a mixture of hydrocarbons and phenols in a still, in conditionsin which the hydrocarbons will pass 01f and .be condensed in the form ofan azeotropic mixture, the phenols remaining behind. v

.The steam distillation may with advantage be carried out with theemployment of a good fractionating column, products of a greatlyimproved and saleable quality containing phenols or tar acids can beproduced directly.

In accordance with the invention, the separation may be efiected bycarrying out the distillation in a still in which is contained arelatively large proportion of water, so that there is always anexcessof water in the still during the operation.

The stil1 should preferably be fitted with a fractionating ordephlegmating column or a reflux or some other form of apparatus whichwill cause a portion of the distillate to reflux and thereby cause theseparation of a distillate consisting mainly of hydrocarbons and water.

Conveniently, in accordance with the invention, the mixture ofhydrocarbons and water distilling over and comparatively free fromphenols, is run into a separator and the separated water returned to thecolumn or other reflux device, or alternatively the distillate can betaken of! and separated at a later stage in which case the addition ofsteam or water in a stepwise or continuous manner to the contents of thestill must be made in order to keep an excess of water in the still.

Where the material to be treated contains parafiinic as well as aromatichydrocarbons, prelerably fractions boiling within a temperature range ofnot exceeding 20 C. and, for instance, a range of 5 C. are treated inwhich case the paramnic hydrocarbons will be'concentrated in thefraction arising towards the final stages in the distillation treatmentin the presence of water.

The distilling operation is carried out until the residual liquid in thestill is sufliciently free from hydrocarbons for the purpose for whichit is intended.

In the later stages of the distillation, some intermediate fractions maybe obtained containing the varying amounts of phenols and otherimpurities such as tar bases.

The tar bases may be removed by well-known methods from such fractionsand the mixture of hydrocarbons and phenols returned to the still forfurther treatment or added to a further charge, which is subjected todistillation in the presence of water.

By the process, in accordance with the invention, saleable phenolfractions can be produced direct from certain mixtures of hydrocarbonoils containing phenols, tar bases, and other impurities.

The following particulars are given by way of examples to illustrate theresult which may be invention.

EXAMPLE I A sample of coal tar naphtha distilling between 175 C. and 195C. was placed in a still with a fractionating column and twice itsvolume of water added. The mixture was fractionated using a dephlegmatoron the top of the column. The distillate was run into a separator andthe water returned to the column as reflux until the separation nolonger took place easily owing to the rising specific gravity of the oilin the distillate. At this point the whole of the distillate was takenoff and the water separated later. The water thus separated can be usedin. the next charge.

Results Sp. 'Ier Hydro- Or. Acids Bases carbons Per cent Per cent Percent Charge 50 gallons .968 33 62 1 20% allons..- .970 l 4 95 2 8gallons..-.. .950 8 8 84 3 5 gallons .91l 26 8 66 4 Bgnllons 1.022 58 1628 5 3gallons... 86 9 5 6 9% gallons residues... 1.067 99.7 0.15 0.15

The residue was taken out of the still, the water separated and the oildistilled. Of the original charge 1% was left as a pitchy residue.

Thus about two-thirds of the hydrocarbons were recovered substantiallyfree from phenols and about two-thirds of the phenols present wererecovered as a marketable product. The intermediaries can be re-workedafter removing the bases or they can be used for other purposes.

EXAMPLE II A crude coal tar naphtha fraction distilling 170 to 175 C.was fractionated in the Presence of water using a separator on the stillhead so that the water separated could be run back down the column asreflux.

The original naphtha tested as follows:

Flask distillation drop 169.5 0., dry 1'75.5 0.

Sp. gr. .954 Parafllns ercent. 14 Tar acids do 34 Bases (10.... 1.2

On fractionation of 45 gallons of the above material under theconditions stated the following fractions were obtained.

Sip. Tar an Acids Bases Parafiins Percent Per cent Per cent 1 Bgnllons.932 1 ii 1.5 2 -.do .942 Nil 1 8 3 d0.. .943 Nil 1.5 4.75 4 .do.. .939Ni] 1.5 6.3 5 ...do.- .880 1.5 2.0 35 6 ...do.. .834 3.5 1.0 62 72gallons .816 4.5 0.5 69 8 13 gallons resi 99.56 0.14 0.3

points supplying them to column 2, to which steam is admitted by way ofthe pipe 3.

In the lower part of this column there is located a re-boiier Theazeotropic mixture passes away from the column in the form of vapour byway of the pipe 5 to a condenser 5 and a separator 1 from which thelower layer, that is water and hydrocarbon, is returned by way of thepipe 8 to the column and the separated hydrocarbon led away through thepipe 9. The distillation residue consisting largely of phenols in thecolumn 2 passes out by way of the pipe in and is delivered to thedistillation column l I to which steam is admitted by way of the pipe H.In this column there is a reboiler i3.

The phenols constitute the distillation residue in this column and theyare withdrawn by way of the pipe I l.

The vapours from the column pass out by way of the pipe l5 and are ledto an analyser l8 and thence into a separator H the lower layer ofliquid formed thereon being returned by way of the pipe iii to thecolumn ll.

A portion of the material separating in the separator I! may bewithdrawn by way of the pipe IQ for re-treatment in the column 2, beingreturned to that column by way of the feed pipe I.

I claim:

1. The process of treating hydrocarbon distillates containing phenolswhich distill along with the hydrocarbons when such distillates arevaporized in the absence of steam which comprises subjecting suchhydrocarbon distillates to distillation in the presence of steam,driving all as vapour the major portion of the hydrocarbon componentswith water in the form of an azeotropic mixture and recovering thephenols in the residual or higher boiling fractions.

2. A process as claimed in claim 1, in which distillation in thepresence of steam is carried out in a continuous manner by running thehydrocarbon. distillates containing phenols down a column up which steamis blown, the hydrocarbons being taken oil at the top and the phenols atthe bottom of the column.

3. A process as claimed in claim 1, in which. steam is blown into a bodyof a mixture of hydrocarbons and phenols in a still whereby the hydrocarbons are driven off in the form of an areatropic mixture and arecondensed, the phenols remaining mainly behind as a residue.

4. The process of treating hydrocarbon. tillates containing phenolswhich distill along with the hydrocarbons when such distillates arevaporized in the absence of steam which comprises subjecting suchhydrocarbon distillates to distillation in the presence of steam.condensing the mixture of hydrocarbons and water distilling over andwhich is comparatively free from phenols, running the mixture into aseparator whereby the hydrocarbons and water are separated and returningthe separated water to the body of material undergoing treatment.

5. Process of treating hydrocarbon distillates containing paraflinic aswell as aromatic hydrocarbons and in addition phenols which distillalong with the hydrocarbons when such distillates are vaporized in theabsence of steam which comprises subjecting the hydrocarbon distillatescontaining both hydrocarbons and phenols in the form of fractionsboiling within a temperature range to distillation in the presence ofsteam, collecting the paraffinic hydrocarbons in concentrated form asfractions arising towards the final stages in the distillation treatmentand the phenols are preponderatingly contained in the residue.

6. The process of treating hydrocarbon distillates containing phenolswhich distill along with the hydrocarbons when such distillates arevaporized in the absence of steam which comprises subjecting suchhydrocarbon distillates to distillatiom in the presence of steam,driving off the major portion of the hydrocarbon components "with waterin the form of an azeotropic mixture, and thereafter subjecting theresidual phenolic residue to distillation in the presence of water.

"7. The process of treating hydrocarbon distillates containing phenolswhich distill along with the hydrocarbons when such distillates arevaporized in the absence of steam which comprises subjecting suchhydrocarbon distillates t0 distillation in the presence of steam,whereby the major portion of the hydrocarbon components are distilledoff with water in the form of an azeotropic mixture, thereafterinterrupting the supply of steam and distilling of! the phenols in thesubstantial absence of water.

10 phenolic material remaining.

DAVID WIILIAM MILNER.

REFERENCES CITED The following references are of record in the file orthis patent:

UNITED STATES PATENTS 20 Number Name Date 2,040,096 Miller May 12, 19362,168,570 Kraft Aug. 8, 1939 2,186,298 Kiersted Jan. 9, 1940 2,370,530G886 Feb. 27, 1945

